Most entrepreneurs do not succeed in their attempt to create a sustainable business from their venture idea. There are several reasons for the very high failure rates in start-up and social entrepreneurship, but most can be traced back to a lack of understanding of how a start-up should be managed in its different phases, from the identification of the opportunity to the management of the established and growing venture. This book analyses the start-up process and suggests theoretical insights, methods and tools that will help the entrepreneur to manage the risk associated with unknowns and uncertainties and that will increase the chances of success. The framework presented, the SMART entrepreneurial process, draws heavily on “modern” entrepreneurial management theory such as the lean start-up method and effectual entrepreneurship, but combines these approaches with suggestions for practical implementation. The book is mainly written with budding for-profit start-uppers in mind, but provides insights that are equally useful for social entrepreneurs.